Dr. Bravo-Cordero obtained his degree in biology at Autonoma University of Madrid, Spain. After completing his doctorate work, in which he used high-resolution confocal imaging techniques to study cancer cell biology, he continued his training in the area of state-of-the-art imaging in the laboratories of Dr. John Condeelis and Dr. Louis Hodgson. During postdoctoral training, Dr. Bravo-Cordero focused on understanding how RhoGTPases are spatiotemporally regulated during breast cancer cell migration and invasion. He w a s trained in techniques such as FRET microscopy as well as FRET biosensors imaging to address these questions. His work to date has resulted in 23 peer-review publications. Recent work has shown that metastasis of tumor cells is affected by the extracellular microenvironment in which the cells are located. In order to understand the mechanisms of tumor cell metastasis and the activation of the intracellular signals, high-resolution microscopy techniques like multiphoton imaging is an ideal modality to observe tumor cells inside their physiological environment. In vitro models are limited in their complexity, thus using animal models that recapitulate the disease, will be a more effective way to address questions that could not be addressed with in vitro systems. Dr. Bravo Cordero has been trained in techniques such as multiphoton in vivo imaging and FRET microscopy in order to understand cell signaling in vivo. This training makes it possible to lead a laboratory that integrates animal models, multiphoton imaging and FRET- biosensor imaging in vivo to understand mechanisms of tumor cell metastasis. Environment: Advisory committee of the PI included Dr. John Condeelis, Co-Chair of Anatomy Department and Biophotonic Center at Einstein. His lab and the Center create a multidisciplinary environment focused on answering mechanisms of human diseases, such as cancer, through use of microscopy. The Center is well known for its shared imaging resources and Innovation Laboratory, in which new microscopes are custom-built to accommodate specific needs of different projects. Other members of the advisory committee are: Dr. Louis Hodgson, he is an expert in FRET biosensor imaging and FRET biosensor design and Dr. Richard Stanley, he is an expert on macrophages biology and CSF-1 receptor signaling, he also studies F-Bar domain proteins in the context of chemotaxis. Dr. Richard Stanley is also a renowned mentor. Einstein is an institution that values collaboration and insists on career development of postdoctoral fellows, instructors and junior faculty. Research: Motility and invasion are crucial steps for multiple processes from development and homeostasis to metastasis. In order for cells to move, they must form membrane extensions to propel themselves through the extracellular matrix. Thus, understanding the molecular pathways that drive spatiotemporal control of protrusion formation is a fundamental question to be answered. The tumor microenvironment is composed of collagen fibers, stromal cells and blood vessels that, in combination, will influence the motility behavior of tumor cells. RhoGTPases are master regulators of cytoskeleton dynamics being tightly regulated by multiple proteins. A family of proteins containing Bar-domains acts at the interface between membrane plasticity and RhoGTPases signaling, and these proteins have emerged as important regulators of GTPases and membrane shape. The final migratory output of a tumor cell will be dictated by the extracellular matrix conditions and that will be translated through a complex signaling system that include BAR proteins and RhoGTPases to induce cytoskeleton rearrangements. Signaling pathways through RhoGTPases have been widely studied in vitro, but the mechanism that regulates GTPase activation in vivo is still unknown. To address the link between tumor microenvironment, motility behavior and RhoGTPases signaling is necessary to combine multiphoton intravital imaging with FRET-biosensors imaging. Two different types of protrusion have been shown to mediate tumor invasion, lamellipodia and invadopodia. To date, it is not clear the contribution of each of them to motility in vivo and tumor intravasation. My preliminary results have shown that tumor cells expressing ?-actin-TagRFP-T as a marker for pseudopodia protrusions show that cell extending membrane protrusion in order to move have enriched in action. Aim 1 will explore how signaling mediated by the GTPases RhoA and RhoC determine the formation of invadopodia and pseudopodia protrusions depending on the extracellular matrix context. By using FRET biosensors in vivo, the activation pattern of these GTPases will be analyzed in these different protrusions. In preliminary experiments the Bar protein srGAP1, which regulates RhoGTPases, is recruited to pseudopodia and invadopodia protrusions of tumor cells. Aim 2 will explore the role of srGAP1 in establishing lamellipodia and invadopodia protrusions through RhoGTPases regulation. Aim 3 will explore the role of srGAP1 in tumor cell dissemination and metastasis in vivo. Results of this study will lead to a better understanding of the interplay among microenvironment components, GTPase signaling and cytoskeleton rearrangements during tumor progression and the results will be used to improve diagnosis and treatment of early metastasis.